1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device, for example, a method for forming a pattern of a semiconductor device by using a double patterning technology, and a semiconductor device.
2. Description of the Prior Art
Memory devices such as flash memory, Dynamic Random Access Memory (DRAM) and Static Random Access Memory (SRAM), or semiconductor devices such as logic device, in recent years, are required to be highly integrated, and therefore miniaturization of patterns is essential. To integrate a lot of devices in a small area, the individual devices should be formed in small size, and therefore both the line width of the pattern to be formed and the fine pitch of spacing thereof should be made small. However, since a photolithography process for forming a desired pattern is limited in resolution, there is a limitation in forming a pattern with a fine pitch.
In recent years, technology (pattern forming technology), which forms a fine pattern on a substrate and processes an under layer of the pattern through an etching process by using the pattern as a mask, is widely applied in IC fabrication of semiconductor industry and attracts a great attention. Therefore, as one of lithography technologies which have been newly proposed, a double patterning method, which forms a photoresist pattern by performing a patterning two or more times, is under investigation. According to this double patterning method, it is considered that a pattern can be formed more finely than a pattern formed by one-time patterning, and, as an example, technology which performs an exposure two or more times is under investigation.
In the double patterning method, in order to form a second photoresist pattern on a first photoresist pattern, it is required to establish a process which does not cause any damage to the first photoresist pattern during the formation of the second photoresist pattern. Specifically, it is required to develop a process technology which overcomes the following problems: (1) deterioration of resistor property, which is caused when a solvent contained in a photoresist penetrates the first photoresist pattern during the formation of the second photoresist pattern; (2) deformation of the first photoresist pattern by a thermal treatment applied during the second photoresist processing (a typical resin-based photoresist material is deformed if it is heated above 150° C.); (3) occurrence of misalignment from a resistor dimension of the first photoresist pattern in a development process during the formation of the second photoresist pattern (practically, a development time becomes as long as a processing time of the second photoresist, thus causing the misalignment from a desired resistor dimension); and (4) occurrence of damage to the first photoresist when rework of the second photoresist processing occurs.